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(fault 8/9) Restructure some code to reduce duplication and simplify flow

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Reviewed by:	dougm, kib, markj
Differential Revision:	https://reviews.freebsd.org/D23321
This commit is contained in:
Jeff Roberson 2020-01-23 05:22:02 +00:00
parent df794f5caf
commit be9d4fd6b4
1 changed files with 39 additions and 41 deletions
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80
sys/vm/vm_fault.c
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@ -1359,49 +1359,47 @@ RetryFault:
* object without dropping the lock to preserve atomicity of
* shadow faults.
*/
if (fs.object->type == OBJT_DEFAULT) {
if (vm_fault_next(&fs))
continue;
/* Don't try to prefault neighboring pages. */
faultcount = 1;
break;
}
if (fs.object->type != OBJT_DEFAULT) {
/*
* At this point, we have either allocated a new page
* or found an existing page that is only partially
* valid.
*
* We hold a reference on the current object and the
* page is exclusive busied. The exclusive busy
* prevents simultaneous faults and collapses while
* the object lock is dropped.
*/
VM_OBJECT_WUNLOCK(fs.object);
/*
* At this point, we have either allocated a new page or found
* an existing page that is only partially valid.
*
* We hold a reference on the current object and the page is
* exclusive busied. The exclusive busy prevents simultaneous
* faults and collapses while the object lock is dropped.
*/
VM_OBJECT_WUNLOCK(fs.object);
/*
* If the pager for the current object might have
* the page, then determine the number of additional
* pages to read and potentially reprioritize
* previously read pages for earlier reclamation.
* These operations should only be performed once per
* page fault. Even if the current pager doesn't
* have the page, the number of additional pages to
* read will apply to subsequent objects in the
* shadow chain.
*/
if (nera == -1 && !P_KILLED(curproc))
nera = vm_fault_readahead(&fs);
/*
* If the pager for the current object might have the page,
* then determine the number of additional pages to read and
* potentially reprioritize previously read pages for earlier
* reclamation. These operations should only be performed
* once per page fault. Even if the current pager doesn't
* have the page, the number of additional pages to read will
* apply to subsequent objects in the shadow chain.
*/
if (nera == -1 && !P_KILLED(curproc))
nera = vm_fault_readahead(&fs);
rv = vm_fault_getpages(&fs, nera, &behind, &ahead);
if (rv == KERN_SUCCESS) {
faultcount = behind + 1 + ahead;
hardfault = true;
break; /* break to PAGE HAS BEEN FOUND. */
}
if (rv == KERN_RESOURCE_SHORTAGE)
goto RetryFault;
VM_OBJECT_WLOCK(fs.object);
if (rv == KERN_OUT_OF_BOUNDS) {
fault_page_free(&fs.m);
unlock_and_deallocate(&fs);
return (rv);
rv = vm_fault_getpages(&fs, nera, &behind, &ahead);
if (rv == KERN_SUCCESS) {
faultcount = behind + 1 + ahead;
hardfault = true;
break; /* break to PAGE HAS BEEN FOUND. */
}
if (rv == KERN_RESOURCE_SHORTAGE)
goto RetryFault;
VM_OBJECT_WLOCK(fs.object);
if (rv == KERN_OUT_OF_BOUNDS) {
fault_page_free(&fs.m);
unlock_and_deallocate(&fs);
return (rv);
}
}
/*